Quarterback of yesteryear dismissing a hated rival, Take 3:Buffalo Bills legend Jim Kelly isn't sold on the Mark Sanchez-Tim Tebow union in Florham Park. He sees chaos on the horizon.

"I gotta be honest: I don't know what (the New York Jets) really were thinking," Kelly told NFL Network's "NFL Total Access" on Thursday. "Mark Sanchez is a quarterback who's going to be sitting there every single game if he plays bad, and No. 1, you know Jets fans -- they're going to start booing."

Mark Sanchez (left) will have Tim Tebow -- not to mention Jets fans -- breathing down his neck all season. (Julio Cortez/Associated Press)

Looking back on his career in Buffalo, Kelly admits he would have questioned his "job security" had the Bills acquired some high-octane media magnet to breathe down his neck. (Frank Reich made a memorable dent in NFL lore, but he understood his place.)

"I think (there's) a lot of pressure on Sanchez to not only start off hot, but continue game after game after game playing steady," Kelly said. "If he doesn't, you know you're going to hear the boo birds. People want Tim Tebow in there.

"I like them both. I thought Sanchez was a very good quarterback coming on. If I was a general manager or president or owner of the team, I wouldn't have done that (trade) unless I got rid of Sanchez. But I think he's a good enough quarterback to be there.

"Tim Tebow's a great athlete who's going to be a big plus for somebody. But in New York? I'm not sure."

This is where we pause to tell you that Kelly remains deeply woven to the Bills' fortunes, admitting, "I hope there's so much turmoil during (Jets) training camp."

The delicious sidenote: The Jets open at home against the Bills. Huge, looming date on the calendar. Don't expect to learn much in preseason about the Sanchez-Tebow dynamic. Week 1 -- at MetLife Stadium, in front of a wild sea of green -- is your acid test.